This invention relates generally to a hub for a pulley, gear, or wheel. More particularly, it relates to such a hub formed with an integral key or other integral means for preventing relative rotation and with an integral stop for positioning the hub axially on a shaft.
1. Background of the Invention
Pulleys have been made by various processes, including casting or machining of the entire pulley and casting or machining of only a tubular boss or hub, and attachment to that tubular boss or hub of a generally disk-shaped body portion, the latter being made by pressing or stamping from metal plate. Pulleys made by the latter methods often have a belt-mounting portion formed by attaching two generally dish-shaped body portions together back-to-back. For many applications, gears may be made by similar methods, with additional steps for cutting gear teeth. The hubs of both pulleys and gears are often made with a keyway machined to extend radially outward from their inner walls for fitting of a key used with a shaft having a keyway machined radially inward from its outer circumference.
2. Description of the Related Art
U.S. Pat. No. 1,266,579 to Garcelon discloses a pulley fabricated by using a hub and welding disks to the hub to form a pulley.
U.S. Pat. No. 3,324,735 to Hanke discloses a pulley fabricated using sheet metal, with elements projecting radially inward from a tubular member. The elements are tapped for setscrews to engage the shaft.
U.S. Pat. No. 4,059,023 to Sproul discloses a one-piece sintered pulley hub construction formed of powder metal with a pair of radially outwardly extending hub pulling flanges. The hub has a generally tubular-shaped body with front and rear end faces and a cylindrical bore extending axially between them. The pulling flanges are formed integrally with the tubular body and extend radially outward from near the front end of the tubular body in diametrically opposite directions, with the front surfaces of the flanges preferably lying in the same plane with the front end face of the tubular body. The flanges provide lugs for gripping by a hub-pulling device, and they enable the hub to be formed in one piece by a powder metal sintering process.
U.S. Pat. Nos. 4,056,014 and 4,090,284 to Kraft discloses a method of making a sintered pulley hub construction for mounting on a bottom wall of a sheet metal pulley cup. A pair of tubular members is pressure-formed in a green compact state from a metal powder mixture. One of the members has a cylindrical body which terminates at one end in an outwardly extending annular flange which forms a hub pulling flange. The other member has an interior annular cavity formed in one end and a radially outwardly extending annular flange formed on the other end. The cylindrical body of the one member is telescopically received within the annular cavity of the other member. The members are joined by sintering to form an integral homogeneous body. The method of forming the improved hub includes the steps of separately pressure-forming each of the tubular members in a green compact state in a pair of molds.
U.S. Pat. No. 4,226,134 to Sohnle discloses a belt pulley constructed using two substantially identical stamped sheet metal halves which are so configured as to define a hub region when assembled. One or both of the pulley halves may be provided with a radially inwardly extending nose which engages a key-way on the shaft on which it is mounted, for preventing relative rotation of pulley and shaft.
U.S. Pat. No. 4,220,372 to Johansen et al. discloses a dual wheel and axle assembly having a wedge lock hub and axle assembly with an auxiliary clamp to augment the grip of the hub on the drive axle. A drive is provided to force bushing segments between the wheel hub and the drive axle to firmly lock the wheel hub and axle together. One of the bushing segments has an extension which extends axially along the drive shaft and carries a clamp in the form of at least one U-bolt having curvature mating that of the peripheral surface of the drive axle. The U-bolt is firmly clamped against a portion of the drive axle while the extension of the bushing segment which has an integral key firmly seats in a key slot of the drive axle to augment the grip of the wheel hub on the drive axle to accommodate additional torque produced by adding dual wheels to a conventional single wheel drive on a tractor.
U.S. Pat. Reissue No. RE32,125 to Von Kaler et al. discloses a transmission for changing speed, with a shift mechanism which selectively couples a plurality of change gears one at a time to a shaft on which the gears are journalled. The shift mechanism is disposed entirely within the transmission housing and includes a shift key arranged for axial sliding movement in a groove in the shaft. Change gears have four integral arcuate teeth, extending inward, to journal the gear on a shaft. The axial dimension of each tooth is slightly less than half the axial dimension of the gear.
U.S. Pat. No. 4,525,094 to Johnson et al. discloses a split-flanged circular bushing to be used to secure driving or driven elements such as sheaves, pulleys, and the like, to a rotatable shaft. The bushing has an integrally formed key in its center opening for insertion into a corresponding keyway in the shaft. The bushing is formed in a sintering operation. Increased density is imparted to fillets or junctions between the flange and the outer wall of the body, thereby providing increased resistance to stress fatigue in these critical areas. Fillets between the key and the inner wall of the body are provided to distribute the stress concentration inherent in these areas.
U.S. Pat. No. 5,527,227 to Asai et al. discloses a pulley made from a metal plate by using a press forming technique. The pulley has a thin tubular boss portion and a disk-shaped body portion which are integral. The boss portion may have a reinforcing flange at one open end portion. The reinforcing flange aids in providing sufficient strength against the tightening force of a nut which is screwed onto a shaft inserted into the boss portion and also disperses the tightening force. The pulley may have a key member formed integrally on the boss portion.
U.S. Pat. No. 5,720,685 to Malone shows a molded plastic pulley and stub shaft for the drive train of a clothes-washing machine. A plastic pulley and stub shaft are integrally formed with one another and used as a unitary component in the drive train of the clothes washing machine. The pulley has a co-axial bore on one side for receiving a motor shaft of an electric motor. The pulley also has a circumferential groove configured for receiving a belt. The stub shaft extends co-axially from the opposite side of the pulley as the bore.
In the assembly of machines using pulleys, the pulleys are sometimes misaligned relative to the ends of their shafts and keys are sometimes inadvertently omitted or lost. Similar problems occur in the use of gears. There is a need for pulleys or gears made to prevent such assembly errors and to improve speed and efficiency of assembling machines.
A major object of the invention is to provide a pulley or gear that has integral means for preventing relative rotation such as an integral key and preferably has an integral stop, to prevent errors in assembly of the pulley or gear on a shaft and to allow rapid, properly aligned assembly. Another object is providing a pulley or gear requiring a reduced number of separate parts, thus reducing inventory-keeping and preventing loss of small individual parts.
A hub for a pulley, gear, or wheel is formed with an integral key or other integral means for preventing relative rotation and with an integral stop for positioning the hub axially on a shaft. The hub has a generally cylindrical (or polygonal) opening for a shaft, an integral key extending inwardly into the shaft opening along at least part of the shaft opening for engaging a keyway in the shaft, and an integral mechanical stop covering at least a portion of one end of the shaft opening. The integral key preferably extends the entire length of the shaft opening. The mechanical stop preferably has an opening which is disposed at least around one end of the integral key. The mechanical stop serves to position the pulley, gear, or wheel precisely with respect to the end of a shaft when the pulley, gear, or wheel is assembled onto the shaft. The keyed hub is manufactured by powder metallurgy. One or more body plates are welded or glued to the formed hub to form a pulley, gear, or wheel, or the hub is pressed into a body plate. The shaft opening may be formed with an integral flat or with a polygonal or splined cross-section to prevent rotation of the hub on its shaft, instead of, or in addition to, the integral key.